21655610402 has 4 divisors (see below), whose sum is σ = 32483415606. Its totient is φ = 10827805200.

The previous prime is 21655610401. The next prime is 21655610407. The reversal of 21655610402 is 20401655612.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 14616568201 + 7039042201 = 120899^2 + 83899^2 .

It is not an unprimeable number, because it can be changed into a prime (21655610401) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5413902599 + ... + 5413902602.

Almost surely, 2^21655610402 is an apocalyptic number.

21655610402 is a deficient number, since it is larger than the sum of its proper divisors (10827805204).

21655610402 is a wasteful number, since it uses less digits than its factorization.

21655610402 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10827805203.

The product of its (nonzero) digits is 14400, while the sum is 32.

The spelling of 21655610402 in words is "twenty-one billion, six hundred fifty-five million, six hundred ten thousand, four hundred two".