21537837 has 12 divisors (see below), whose sum is σ = 31203900. Its totient is φ = 14315328.

The previous prime is 21537787. The next prime is 21537851. The reversal of 21537837 is 73873512.

It can be written as a sum of positive squares in 2 ways, for example, as 6022116 + 15515721 = 2454^2 + 3939^2 .

It is not a de Polignac number, because 21537837 - 2¹⁴ = 21521453 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21537137) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 288 + ... + 6569.

It is an arithmetic number, because the mean of its divisors is an integer number (2600325).

Almost surely, 2^21537837 is an apocalyptic number.

It is an amenable number.

21537837 is a deficient number, since it is larger than the sum of its proper divisors (9666063).

21537837 is a wasteful number, since it uses less digits than its factorization.

21537837 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7212 (or 7209 counting only the distinct ones).

The product of its digits is 35280, while the sum is 36.

The square root of 21537837 is about 4640.8875228775. The cubic root of 21537837 is about 278.2279111988.

The spelling of 21537837 in words is "twenty-one million, five hundred thirty-seven thousand, eight hundred thirty-seven".