21493090 has 32 divisors (see below), whose sum is σ = 39890880. Its totient is φ = 8334144.

The previous prime is 21493079. The next prime is 21493091. The reversal of 21493090 is 9039412.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (21493091) 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, 56521 + ... + 56899.

It is an arithmetic number, because the mean of its divisors is an integer number (1246590).

Almost surely, 2^21493090 is an apocalyptic number.

21493090 is a deficient number, since it is larger than the sum of its proper divisors (18397790).

21493090 is a wasteful number, since it uses less digits than its factorization.

21493090 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 546.

The product of its (nonzero) digits is 1944, while the sum is 28.

The square root of 21493090 is about 4636.0640634055. The cubic root of 21493090 is about 278.0350955468.

The spelling of 21493090 in words is "twenty-one million, four hundred ninety-three thousand, ninety".