21690021490 has 16 divisors (see below), whose sum is σ = 39142410840. Its totient is φ = 8653703680.

The previous prime is 21690021487. The next prime is 21690021527. The reversal of 21690021490 is 9412009612.

It can be written as a sum of positive squares in 4 ways, for example, as 20429842489 + 1260179001 = 142933^2 + 35499^2 .

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, 2784031 + ... + 2791810.

Almost surely, 2^21690021490 is an apocalyptic number.

21690021490 is a deficient number, since it is larger than the sum of its proper divisors (17452389350).

21690021490 is a wasteful number, since it uses less digits than its factorization.

21690021490 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5576237.

The product of its (nonzero) digits is 7776, while the sum is 34.

The spelling of 21690021490 in words is "twenty-one billion, six hundred ninety million, twenty-one thousand, four hundred ninety".