21682949 has 4 divisors (see below), whose sum is σ = 21737964. Its totient is φ = 21627936.

The previous prime is 21682937. The next prime is 21682963. The reversal of 21682949 is 94928612.

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 14010049 + 7672900 = 3743^2 + 2770^2 .

It is a cyclic number.

It is not a de Polignac number, because 21682949 - 2⁸ = 21682693 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 (21682909) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 26912 + ... + 27705.

It is an arithmetic number, because the mean of its divisors is an integer number (5434491).

Almost surely, 2^21682949 is an apocalyptic number.

It is an amenable number.

21682949 is a deficient number, since it is larger than the sum of its proper divisors (55015).

21682949 is an equidigital number, since it uses as much as digits as its factorization.

21682949 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 55014.

The product of its digits is 62208, while the sum is 41.

The square root of 21682949 is about 4656.4953559517. The cubic root of 21682949 is about 278.8513701574.

The spelling of 21682949 in words is "twenty-one million, six hundred eighty-two thousand, nine hundred forty-nine".