21389510 has 16 divisors (see below), whose sum is σ = 38576736. Its totient is φ = 8539008.

The previous prime is 21389509. The next prime is 21389521. The reversal of 21389510 is 1598312.

It is a super-2 number, since 2×21389510² = 915022276080200, which contains 22 as substring.

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, 4127 + ... + 7733.

It is an arithmetic number, because the mean of its divisors is an integer number (2411046).

Almost surely, 2^21389510 is an apocalyptic number.

21389510 is a deficient number, since it is larger than the sum of its proper divisors (17187226).

21389510 is a wasteful number, since it uses less digits than its factorization.

21389510 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4207.

The product of its (nonzero) digits is 2160, while the sum is 29.

The square root of 21389510 is about 4624.8794578886. The cubic root of 21389510 is about 277.5877384010.

The spelling of 21389510 in words is "twenty-one million, three hundred eighty-nine thousand, five hundred ten".