21980856 has 16 divisors (see below), whose sum is σ = 54952200. Its totient is φ = 7326944.

The previous prime is 21980851. The next prime is 21980857. The reversal of 21980856 is 65808912.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21980851) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 457911 + ... + 457958.

Almost surely, 2^21980856 is an apocalyptic number.

It is an amenable number.

21980856 is an abundant number, since it is smaller than the sum of its proper divisors (32971344).

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

21980856 is a wasteful number, since it uses less digits than its factorization.

21980856 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 915878 (or 915874 counting only the distinct ones).

The product of its (nonzero) digits is 34560, while the sum is 39.

The square root of 21980856 is about 4688.3745584157. The cubic root of 21980856 is about 280.1226333565.

The spelling of 21980856 in words is "twenty-one million, nine hundred eighty thousand, eight hundred fifty-six".