21503490 has 16 divisors (see below), whose sum is σ = 51608448. Its totient is φ = 5734256.

The previous prime is 21503479. The next prime is 21503527. The reversal of 21503490 is 9430512.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21503490.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 358362 + ... + 358421.

It is an arithmetic number, because the mean of its divisors is an integer number (3225528).

Almost surely, 2^21503490 is an apocalyptic number.

21503490 is an abundant number, since it is smaller than the sum of its proper divisors (30104958).

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

21503490 is a wasteful number, since it uses less digits than its factorization.

21503490 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 716793.

The product of its (nonzero) digits is 1080, while the sum is 24.

The square root of 21503490 is about 4637.1855688553. The cubic root of 21503490 is about 278.0799331936.

The spelling of 21503490 in words is "twenty-one million, five hundred three thousand, four hundred ninety".