21372549 has 32 divisors (see below), whose sum is σ = 33177600. Its totient is φ = 12101760.

The previous prime is 21372541. The next prime is 21372551. The reversal of 21372549 is 94527312.

It is not a de Polignac number, because 21372549 - 2³ = 21372541 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21372541) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 55612 + ... + 55994.

It is an arithmetic number, because the mean of its divisors is an integer number (1036800).

Almost surely, 2^21372549 is an apocalyptic number.

It is an amenable number.

21372549 is a deficient number, since it is larger than the sum of its proper divisors (11805051).

21372549 is a wasteful number, since it uses less digits than its factorization.

21372549 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 505.

The product of its digits is 15120, while the sum is 33.

The square root of 21372549 is about 4623.0454248255. The cubic root of 21372549 is about 277.5143471196.

The spelling of 21372549 in words is "twenty-one million, three hundred seventy-two thousand, five hundred forty-nine".