21356949 has 8 divisors (see below), whose sum is σ = 29714112. Its totient is φ = 13618880.

The previous prime is 21356927. The next prime is 21356971. The reversal of 21356949 is 94965312.

It is an interprime number because it is at equal distance from previous prime (21356927) and next prime (21356971).

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

It is a cyclic number.

It is not a de Polignac number, because 21356949 - 2⁵ = 21356917 is a prime.

It is a super-2 number, since 2×21356949² = 912238541177202, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21356989) 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, 154692 + ... + 154829.

It is an arithmetic number, because the mean of its divisors is an integer number (3714264).

Almost surely, 2^21356949 is an apocalyptic number.

It is an amenable number.

21356949 is a deficient number, since it is larger than the sum of its proper divisors (8357163).

21356949 is a wasteful number, since it uses less digits than its factorization.

21356949 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 309547.

The product of its digits is 58320, while the sum is 39.

The square root of 21356949 is about 4621.3579173226. The cubic root of 21356949 is about 277.4468106806.

The spelling of 21356949 in words is "twenty-one million, three hundred fifty-six thousand, nine hundred forty-nine".