21537879 has 12 divisors (see below), whose sum is σ = 31565688. Its totient is φ = 13053040.

The previous prime is 21537871. The next prime is 21537881. The reversal of 21537879 is 97873512.

It is not a de Polignac number, because 21537879 - 2³ = 21537871 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21537879.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21537871) 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 11 ways as a sum of consecutive naturals, for example, 29304 + ... + 30029.

It is an arithmetic number, because the mean of its divisors is an integer number (2630474).

Almost surely, 2^21537879 is an apocalyptic number.

21537879 is a deficient number, since it is larger than the sum of its proper divisors (10027809).

21537879 is a wasteful number, since it uses less digits than its factorization.

21537879 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 59358 (or 59347 counting only the distinct ones).

The product of its digits is 105840, while the sum is 42.

The square root of 21537879 is about 4640.8920478718. The cubic root of 21537879 is about 278.2280920521.

The spelling of 21537879 in words is "twenty-one million, five hundred thirty-seven thousand, eight hundred seventy-nine".