21641540 has 24 divisors (see below), whose sum is σ = 47015640. Its totient is φ = 8357888.

The previous prime is 21641537. The next prime is 21641579. The reversal of 21641540 is 4514612.

It can be written as a sum of positive squares in 4 ways, for example, as 8667136 + 12974404 = 2944^2 + 3602^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 18077 + ... + 19236.

It is an arithmetic number, because the mean of its divisors is an integer number (1958985).

Almost surely, 2^21641540 is an apocalyptic number.

21641540 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21641540 is an abundant number, since it is smaller than the sum of its proper divisors (25374100).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21641540 is a wasteful number, since it uses less digits than its factorization.

21641540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37351 (or 37349 counting only the distinct ones).

The product of its (nonzero) digits is 960, while the sum is 23.

The square root of 21641540 is about 4652.0468613289. The cubic root of 21641540 is about 278.6737449522.

The spelling of 21641540 in words is "twenty-one million, six hundred forty-one thousand, five hundred forty".