20921221964 has 6 divisors (see below), whose sum is σ = 36612138444. Its totient is φ = 10460610980.

The previous prime is 20921221949. The next prime is 20921221969. The reversal of 20921221964 is 46912212902.

It is not an unprimeable number, because it can be changed into a prime (20921221969) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2615152742 + ... + 2615152749.

It is an arithmetic number, because the mean of its divisors is an integer number (6102023074).

Almost surely, 2^20921221964 is an apocalyptic number.

It is an amenable number.

20921221964 is a deficient number, since it is larger than the sum of its proper divisors (15690916480).

20921221964 is a wasteful number, since it uses less digits than its factorization.

20921221964 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5230305495 (or 5230305493 counting only the distinct ones).

The product of its (nonzero) digits is 31104, while the sum is 38.

The spelling of 20921221964 in words is "twenty billion, nine hundred twenty-one million, two hundred twenty-one thousand, nine hundred sixty-four".