21802137 has 16 divisors (see below), whose sum is σ = 34667520. Its totient is φ = 11916432.

The previous prime is 21802129. The next prime is 21802141. The reversal of 21802137 is 73120812.

It is not a de Polignac number, because 21802137 - 2³ = 21802129 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21802117) 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, 22087 + ... + 23052.

It is an arithmetic number, because the mean of its divisors is an integer number (2166720).

Almost surely, 2^21802137 is an apocalyptic number.

It is an amenable number.

21802137 is a deficient number, since it is larger than the sum of its proper divisors (12865383).

21802137 is a wasteful number, since it uses less digits than its factorization.

21802137 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 45172.

The product of its (nonzero) digits is 672, while the sum is 24.

The square root of 21802137 is about 4669.2758539200. The cubic root of 21802137 is about 279.3613718960.

Adding to 21802137 its reverse (73120812), we get a palindrome (94922949).

The spelling of 21802137 in words is "twenty-one million, eight hundred two thousand, one hundred thirty-seven".