21693545 has 4 divisors (see below), whose sum is σ = 26032260. Its totient is φ = 17354832.

The previous prime is 21693527. The next prime is 21693557. The reversal of 21693545 is 54539612.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 6801664 + 14891881 = 2608^2 + 3859^2 .

It is a cyclic number.

It is not a de Polignac number, because 21693545 - 2¹² = 21689449 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2169350 + ... + 2169359.

It is an arithmetic number, because the mean of its divisors is an integer number (6508065).

Almost surely, 2^21693545 is an apocalyptic number.

It is an amenable number.

21693545 is a deficient number, since it is larger than the sum of its proper divisors (4338715).

21693545 is an equidigital number, since it uses as much as digits as its factorization.

21693545 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4338714.

The product of its digits is 32400, while the sum is 35.

The square root of 21693545 is about 4657.6329825352. The cubic root of 21693545 is about 278.8967856887.

The spelling of 21693545 in words is "twenty-one million, six hundred ninety-three thousand, five hundred forty-five".