21020790021 has 32 divisors (see below), whose sum is σ = 34953335808. Its totient is φ = 10916864640.

The previous prime is 21020790013. The next prime is 21020790029. The reversal of 21020790021 is 12009702012.

It is an interprime number because it is at equal distance from previous prime (21020790013) and next prime (21020790029).

It is not a de Polignac number, because 21020790021 - 2³ = 21020790013 is a prime.

It is a super-2 number, since 2×21020790021² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21020789973 and 21020790000.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21020790029) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 997425 + ... + 1018281.

It is an arithmetic number, because the mean of its divisors is an integer number (1092291744).

Almost surely, 2^21020790021 is an apocalyptic number.

21020790021 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21020790021 is a deficient number, since it is larger than the sum of its proper divisors (13932545787).

21020790021 is a wasteful number, since it uses less digits than its factorization.

21020790021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25241.

The product of its (nonzero) digits is 504, while the sum is 24.

The spelling of 21020790021 in words is "twenty-one billion, twenty million, seven hundred ninety thousand, twenty-one".