21990510 has 24 divisors (see below), whose sum is σ = 57175560. Its totient is φ = 5864112.

The previous prime is 21990509. The next prime is 21990517. The reversal of 21990510 is 1509912.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21990517) 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, 122080 + ... + 122259.

It is an arithmetic number, because the mean of its divisors is an integer number (2382315).

Almost surely, 2^21990510 is an apocalyptic number.

21990510 is an abundant number, since it is smaller than the sum of its proper divisors (35185050).

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

21990510 is a wasteful number, since it uses less digits than its factorization.

21990510 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 244352 (or 244349 counting only the distinct ones).

The product of its (nonzero) digits is 810, while the sum is 27.

The square root of 21990510 is about 4689.4040133049. The cubic root of 21990510 is about 280.1636373418.

It can be divided in two parts, 21990 and 510, that added together give a square (22500 = 150²).

The spelling of 21990510 in words is "twenty-one million, nine hundred ninety thousand, five hundred ten".