21177640 has 32 divisors (see below), whose sum is σ = 51982560. Its totient is φ = 7700800.

The previous prime is 21177617. The next prime is 21177649. The reversal of 21177640 is 4677112.

It is a junction number, because it is equal to n+sod(n) for n = 21177599 and 21177608.

It is not an unprimeable number, because it can be changed into a prime (21177649) 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, 23626 + ... + 24505.

It is an arithmetic number, because the mean of its divisors is an integer number (1624455).

Almost surely, 2^21177640 is an apocalyptic number.

21177640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21177640 is an abundant number, since it is smaller than the sum of its proper divisors (30804920).

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

21177640 is a wasteful number, since it uses less digits than its factorization.

21177640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 48153 (or 48149 counting only the distinct ones).

The product of its (nonzero) digits is 2352, while the sum is 28.

The square root of 21177640 is about 4601.9169918633. The cubic root of 21177640 is about 276.6681634086.

The spelling of 21177640 in words is "twenty-one million, one hundred seventy-seven thousand, six hundred forty".