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BaseRepresentation
bin1011111010101…
…11001011101101
320222010002120001
411331113023231
5201043044241
613530424301
72322514015
oct575271355
9228102501
1099971821
1151482344
1229592091
1317933a31
14d3c4c45
158b9b431
hex5f572ed

99971821 has 8 divisors (see below), whose sum is σ = 101514680. Its totient is φ = 98433792.

The previous prime is 99971813. The next prime is 99971827. The reversal of 99971821 is 12817999.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 1188100 + 98783721 = 1090^2 + 9939^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a 4-Lehmer number, since φ(99971821) divides (99971821-1)4.

It is a cyclic number.

It is not a de Polignac number, because 99971821 - 23 = 99971813 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (99971827) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 81811 + ... + 83023.

It is an arithmetic number, because the mean of its divisors is an integer number (12689335).

It is a Poulet number, since it divides 299971820-1.

Almost surely, 299971821 is an apocalyptic number.

It is an amenable number.

99971821 is a deficient number, since it is larger than the sum of its proper divisors (1542859).

99971821 is a wasteful number, since it uses less digits than its factorization.

99971821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2415.

The product of its digits is 81648, while the sum is 46.

The square root of 99971821 is about 9998.5909507290. The cubic root of 99971821 is about 464.1152808215.

The spelling of 99971821 in words is "ninety-nine million, nine hundred seventy-one thousand, eight hundred twenty-one".

Divisors: 1 73 1129 1213 82417 88549 1369477 99971821