21390993352 has 8 divisors (see below), whose sum is σ = 40108112550. Its totient is φ = 10695496672.

The previous prime is 21390993317. The next prime is 21390993353. The reversal of 21390993352 is 25339909312.

It can be written as a sum of positive squares in only one way, i.e., 15379472196 + 6011521156 = 124014^2 + 77534^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is not an unprimeable number, because it can be changed into a prime (21390993353) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1336937077 + ... + 1336937092.

Almost surely, 2^21390993352 is an apocalyptic number.

It is an amenable number.

21390993352 is a deficient number, since it is larger than the sum of its proper divisors (18717119198).

21390993352 is a wasteful number, since it uses less digits than its factorization.

21390993352 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2673874175 (or 2673874171 counting only the distinct ones).

The product of its (nonzero) digits is 393660, while the sum is 46.

The spelling of 21390993352 in words is "twenty-one billion, three hundred ninety million, nine hundred ninety-three thousand, three hundred fifty-two".