21640401420 has 48 divisors (see below), whose sum is σ = 66101591808. Its totient is φ = 5246157760.

The previous prime is 21640401403. The next prime is 21640401463. The reversal of 21640401420 is 2410404612.

It is a happy number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 16393584 + ... + 16394903.

It is an arithmetic number, because the mean of its divisors is an integer number (1377116496).

Almost surely, 2^21640401420 is an apocalyptic number.

21640401420 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21640401420 is an abundant number, since it is smaller than the sum of its proper divisors (44461190388).

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

21640401420 is a wasteful number, since it uses less digits than its factorization.

21640401420 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32788510 (or 32788508 counting only the distinct ones).

The product of its (nonzero) digits is 1536, while the sum is 24.

The spelling of 21640401420 in words is "twenty-one billion, six hundred forty million, four hundred one thousand, four hundred twenty".