1020021921 has 12 divisors (see below), whose sum is σ = 1475321172. Its totient is φ = 679111776.

The previous prime is 1020021911. The next prime is 1020021953. The reversal of 1020021921 is 1291200201.

It can be written as a sum of positive squares in 2 ways, for example, as 217149696 + 802872225 = 14736^2 + 28335^2 .

It is not a de Polignac number, because 1020021921 - 2⁶ = 1020021857 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 1020021894 and 1020021903.

It is not an unprimeable number, because it can be changed into a prime (1020021911) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 68046 + ... + 81671.

It is an arithmetic number, because the mean of its divisors is an integer number (122943431).

Almost surely, 2^1020021921 is an apocalyptic number.

It is an amenable number.

1020021921 is a deficient number, since it is larger than the sum of its proper divisors (455299251).

1020021921 is a wasteful number, since it uses less digits than its factorization.

1020021921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 150480 (or 150477 counting only the distinct ones).

The product of its (nonzero) digits is 72, while the sum is 18.

The square root of 1020021921 is about 31937.7820300659. The cubic root of 1020021921 is about 1006.6299206772.

The spelling of 1020021921 in words is "one billion, twenty million, twenty-one thousand, nine hundred twenty-one".