21151672 has 64 divisors (see below), whose sum is σ = 45100800. Its totient is φ = 9246720.

The previous prime is 21151661. The next prime is 21151673. The reversal of 21151672 is 27615112.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21151673) 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, 122178 + ... + 122350.

It is an arithmetic number, because the mean of its divisors is an integer number (704700).

Almost surely, 2^21151672 is an apocalyptic number.

It is an amenable number.

21151672 is an abundant number, since it is smaller than the sum of its proper divisors (23949128).

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

21151672 is a wasteful number, since it uses less digits than its factorization.

21151672 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 256 (or 252 counting only the distinct ones).

The product of its digits is 840, while the sum is 25.

The square root of 21151672 is about 4599.0946935239. The cubic root of 21151672 is about 276.5550337521. Note that the first 3 decimals are identical.

Adding to 21151672 its reverse (27615112), we get a palindrome (48766784).

The spelling of 21151672 in words is "twenty-one million, one hundred fifty-one thousand, six hundred seventy-two".