21612801 has 32 divisors (see below), whose sum is σ = 35573760. Its totient is φ = 11398464.

The previous prime is 21612769. The next prime is 21612827. The reversal of 21612801 is 10821612.

It is not a de Polignac number, because 21612801 - 2⁵ = 21612769 is a prime.

It is a super-2 number, since 2×21612801² = 934226334131202, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is not an unprimeable number, because it can be changed into a prime (21612841) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 13236 + ... + 14778.

It is an arithmetic number, because the mean of its divisors is an integer number (1111680).

Almost surely, 2^21612801 is an apocalyptic number.

21612801 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21612801 is a deficient number, since it is larger than the sum of its proper divisors (13960959).

21612801 is a wasteful number, since it uses less digits than its factorization.

21612801 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1605.

The product of its (nonzero) digits is 192, while the sum is 21.

The square root of 21612801 is about 4648.9569797967. The cubic root of 21612801 is about 278.5503348732.

The spelling of 21612801 in words is "twenty-one million, six hundred twelve thousand, eight hundred one".