21988770 has 16 divisors (see below), whose sum is σ = 52773120. Its totient is φ = 5863664.

The previous prime is 21988763. The next prime is 21988777. The reversal of 21988770 is 7788912.

It is an interprime number because it is at equal distance from previous prime (21988763) and next prime (21988777).

It is a super-2 number, since 2×21988770² = 967012012225800, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21988777) 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, 366450 + ... + 366509.

It is an arithmetic number, because the mean of its divisors is an integer number (3298320).

Almost surely, 2^21988770 is an apocalyptic number.

21988770 is an abundant number, since it is smaller than the sum of its proper divisors (30784350).

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

21988770 is a wasteful number, since it uses less digits than its factorization.

21988770 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 732969.

The product of its (nonzero) digits is 56448, while the sum is 42.

The square root of 21988770 is about 4689.2184849930. The cubic root of 21988770 is about 280.1562478271.

The spelling of 21988770 in words is "twenty-one million, nine hundred eighty-eight thousand, seven hundred seventy".