21155953 has 16 divisors (see below), whose sum is σ = 26361216. Its totient is φ = 16531200.

The previous prime is 21155921. The next prime is 21155977. The reversal of 21155953 is 35955112.

It is not a de Polignac number, because 21155953 - 2⁵ = 21155921 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21155903) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 6153 + ... + 8953.

It is an arithmetic number, because the mean of its divisors is an integer number (1647576).

Almost surely, 2^21155953 is an apocalyptic number.

It is an amenable number.

21155953 is a deficient number, since it is larger than the sum of its proper divisors (5205263).

21155953 is a wasteful number, since it uses less digits than its factorization.

21155953 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2904.

The product of its digits is 6750, while the sum is 31.

The square root of 21155953 is about 4599.5600876606. The cubic root of 21155953 is about 276.5736903108.

The spelling of 21155953 in words is "twenty-one million, one hundred fifty-five thousand, nine hundred fifty-three".