21706490 has 16 divisors (see below), whose sum is σ = 42077448. Its totient is φ = 8014656.

The previous prime is 21706463. The next prime is 21706519. The reversal of 21706490 is 9460712.

It can be written as a sum of positive squares in 4 ways, for example, as 11202409 + 10504081 = 3347^2 + 3241^2 .

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, 83357 + ... + 83616.

Almost surely, 2^21706490 is an apocalyptic number.

21706490 is a deficient number, since it is larger than the sum of its proper divisors (20370958).

21706490 is a wasteful number, since it uses less digits than its factorization.

21706490 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 166993.

The product of its (nonzero) digits is 3024, while the sum is 29.

The square root of 21706490 is about 4659.0224296520. The cubic root of 21706490 is about 278.9522492073.

The spelling of 21706490 in words is "twenty-one million, seven hundred six thousand, four hundred ninety".