21129402940 has 24 divisors (see below), whose sum is σ = 45208951200. Its totient is φ = 8292293568.

The previous prime is 21129402937. The next prime is 21129402947. The reversal of 21129402940 is 4920492112.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 21129402896 and 21129402905.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21129402947) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9965640 + ... + 9967759.

It is an arithmetic number, because the mean of its divisors is an integer number (1883706300).

Almost surely, 2^21129402940 is an apocalyptic number.

21129402940 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21129402940 is an abundant number, since it is smaller than the sum of its proper divisors (24079548260).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21129402940 is a wasteful number, since it uses less digits than its factorization.

21129402940 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19933461 (or 19933459 counting only the distinct ones).

The product of its (nonzero) digits is 10368, while the sum is 34.

The spelling of 21129402940 in words is "twenty-one billion, one hundred twenty-nine million, four hundred two thousand, nine hundred forty".