21907680 has 48 divisors (see below), whose sum is σ = 69010704. Its totient is φ = 5841920.

The previous prime is 21907643. The next prime is 21907693. The reversal of 21907680 is 8670912.

It is a tau number, because it is divible by the number of its divisors (48).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 22341 + ... + 23300.

It is an arithmetic number, because the mean of its divisors is an integer number (1437723).

Almost surely, 2^21907680 is an apocalyptic number.

21907680 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21907680 is an abundant number, since it is smaller than the sum of its proper divisors (47103024).

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

21907680 is a wasteful number, since it uses less digits than its factorization.

21907680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 45659 (or 45651 counting only the distinct ones).

The product of its (nonzero) digits is 6048, while the sum is 33.

The square root of 21907680 is about 4680.5640685712. The cubic root of 21907680 is about 279.8114376695.

It can be divided in two parts, 2190 and 7680, that added together give a triangular number (9870 = T₁₄₀).

The spelling of 21907680 in words is "twenty-one million, nine hundred seven thousand, six hundred eighty".